Picture of the internals of a Spectra Physics Hurricane Ti-Sapphire amplifier. As you know, we use high powered green as a pump to achieve IR (how ironic) We recently had our hurricane serviced and recalibrated, so I took the opportunity to grab a photo of the inside of it for you.

The seed laser is a SP Mai-Tai tunable femto second pulse laser, set at 800nm (the white box at the top of the picture). The pump is a SP Evolution ND:YV04 at 532nm, max power is 15W, but as you can see, we are running it at 9W for the calibration procedure. The output from the green pump is split into 2 and polarised and pump both ends of a rod of Titanium Sapphire (the red and yellow glow at the centre). The short pulses from the Mai-Tai are first expanded to reduce the energy before being directed into the Sapphire (you can make out the IR on 2 of the mirrors, it appears purple as seen by my cell phone). The IR pulse travels back and forth through the Sahhire rod about 20 times until it has achieved its maximum gain, it is then released and is shunted to the series of prisms and gratings to the right of the picture to compress the pulse back to its original duration.

The peak power of each pulse is in the region of several hundred KW. Its a bit more complicated than that, but that is basically the theory behind the Ti-Sapphire amplifier / oscillator.